1. Field of the Invention
The invention relates to a thin film magnetic head comprising at least an inductive-type magnetoresistive transducer for writing and a method of manufacturing the same.
2. Description of the Related Art
In recent years, performance improvement in thin film magnetic heads has been sought in accordance with an increase in surface recording density of a hard disk drive. As a thin film magnetic head, a composite thin film magnetic head has been widely used. A composite thin film magnetic head has a layered structure which includes a recording head with an inductive-type transducer for writing and a reproducing head with a magnetoresistive device (also referred to as MR device in the followings) for reading-out. There are a few types of MR devices: one is an AMR device that utilizes the anisotropic magnetoresistance effect (referred to as AMR effect in the followings) and the other is a GMR device that utilizes the giant magnetoresistance effect (referred to as GMR effect in the followings). A reproducing head using an AMR device is called an AMR head or simply an MR head. A reproducing head using the GMR device is called a GMR head. The AMR head is used as a reproducing head whose surface recording density is more than 1 gigabit per square inch. The GMR head is used as a reproducing head whose surface recording density is more than 3 gigabit per square inch.
An AMR head includes an AMR film having the AMR effect. The GMR head has the similar configuration to the AMR head except that the AMR film is replaced with a GMR film having the GMR effect. However, compared to the AMR film, the GMR film exhibits a greater change in resistance under a specific external magnetic field. Accordingly, the reproducing output of the GMR head becomes about three to five times greater than that of the AMR head.
In order to improve the performance of a reproducing head, the MR film may be changed from an AMR film to a GMR film or the like which is made of a material with more excellent magnetoresistive sensitivity, or the pattern width of the MR film. Specifically the MR height may be adjusted appropriate. The MR height is the length (height) between the end of an MR device closer to an air bearing surface and the other end, and is determined by an amount of grinding when the air bearing surface is processed. The air bearing surface (ABS) is a surface of a thin film magnetic head facing a magnetic recording medium and is also called a track surface.
Performance improvement in a recording head has also been expected in accordance with the performance improvement in a reproducing head. The main factor which determines the performance of a recording head is the throat height (TH). The throat height is the length (height) of a portion of a magnetic pole from the air bearing surface to an edge of an insulating layer which electrically isolates the thin film coil. It is necessary to optimize the throat height in order to improve the performance of a recording head. The throat height is also controlled by an amount of grinding when the air bearing surface is processed.
It is necessary to increase the track density of a magnetic recording medium in order to increase the recording density among the performance of a recording head. In order to achieve this, a recording head with a narrow track structure in which the width of a bottom pole and a top pole sandwiching a write gap on the air bearing surface is required to be reduced to the order of some microns to submicron. Semiconductor process technique is used to achieve the narrow track structure.
A composite thin film magnetic head comprising a recording head and a reproducing head described above can be manufactured through a plurality of manufacturing steps such as sputtering, photolithography, electro-plating, etching, polishing and the like.
It is a problem that it requires a long lead-time to manufacture a thin film magnetic head through a series of manufacturing process including a various kinds of steps as described above. Specific improvement of methods such as reducing the number of steps is necessary in order to further shorten the lead-time in a case of mass production.